1. Field of the Invention
The present invention relates to polypeptides having xylanase activity and polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.
2. Description of the Related Art
Cellulose is a polymer of glucose linked by beta-1,4-bonds. Many microorganisms produce enzymes that hydrolyze beta-linked glucans. These enzymes include endoglucanases, cellobiohydrolases, and beta-glucosidases. Endoglucanases digest the cellulose polymer at random locations, opening it to attack by cellobiohydrolases. Cellobiohydrolases sequentially release molecules of cellobiose from the ends of the cellulose polymer. Cellobiose is a water-soluble beta-1,4-linked dimer of glucose. Beta-glucosidases hydrolyze cellobiose to glucose.
The conversion of lignocellulosic feedstocks into ethanol has the advantages of the ready availability of large amounts of feedstock, the desirability of avoiding burning or land filling the materials, and the cleanliness of the ethanol fuel. Wood, agricultural residues, herbaceous crops, and municipal solid wastes have been considered as feedstocks for ethanol production. These materials primarily consist of cellulose, hemicellulose, and lignin. Once the cellulose is converted to glucose, the glucose is easily fermented by yeast into ethanol. Xylanases degrade beta-1,4-xylan into xylose, thus breaking down hemicellulose, one of the major components of plant cell walls.
There is a need in the art to improve cellulolytic and hemicellulolytic enzyme compositions through supplementation with additional enzymes to increase efficiency and to provide cost-effective enzyme solutions for degradation of lignocellulose. Xylanases are known from the prior art. A xylanase from Penicillium canescens (Uniprot. C3VEV9) has 76.1% identity to the xylanase disclosed as SEQ ID NO: 2. Another xylanase from Talaromyces stipitatus (Uniprot. B8M9H8) has 76.5% identity to the xylanase disclosed as SEQ ID NO: 4. Another xylanase from Penicillium sp (Uniprot. AYB51189) disclosed in US2010124769-A1 has 84.0% identity to the xylanase disclosed as SEQ ID NO: 6.
The present invention provides polypeptides having xylanase activity and polynucleotides encoding the polypeptides.